This application claims priority under 35 USC 119(a) to Patent Application No. 2003-082912 filed in Japan on 25 Mar. 2003, the content of which is incorporated herein by reference in its entirety.
The present invention pertains to an optoelectronic dust sensor detecting presence, absence, and/or concentration of dust and/or smoke floating within room(s), and to air conditioning equipment in which such optoelectronic dust sensor(s) is/are installed.
Optoelectronic dust sensors of this type may be provided, for example, at air filters, air scrubbers, air coolers, and other such air conditioning equipment, where they are used to detect presence, absence, and/or concentration of dust and/or smoke contained within air circulated by air conditioning equipment.
FIG. 6(a), FIG. 6(b), FIG. 6(c), and FIG. 6(d) are a sectional view, front view, bottom view, and rear view showing a conventional optoelectronic dust sensor (see Japanese Patent Application Publication Kokai No. H8-62136 (1996). At this sensor, dust passage holes 102a, 103a are respectively formed at front panel 102 and back panel 103 of main body housing 101; dust being introduced from dust passage hole 103a at the back thereof, the dust being made to pass through a dust passage route between respective dust passage holes 102a, 103a, and the dust being discharged from dust passage hole 102a at the front thereof. Light-emitting unit 104 is equipped with light-emitting element 104a, lens 104b, and slit 104c; light from light-emitting element 104a being collimated by lens 104b and thereafter being incident on the dust passage route. Light-receiving unit 105 is equipped with light-receiving element 105a, lens 105b, and slit 105c; light from the dust passage route being condensed onto light-receiving element 105a by
Here, in the event that there is no dust or smoke passing through the dust passage route, because almost all of the light from light-emitting unit 104 will pass through the dust passage route and reach optical isolation region 106, the amount of light received at light-receiving unit 105 will be extremely small. Furthermore, in the event that there is dust and/or smoke passing through the dust passage route, because a portion of the light from light-emitting unit 104 will be reflected by the dust and/or smoke in the dust passage route and will be incident on light-receiving unit 105, the amount of light received at light-receiving unit 105 will increase. Accordingly, presence and/or absence of dust and/or smoke passing through the dust passage route may be detected based on variation in received-light output at light-receiving element 105a of light-receiving unit 105; and/or concentration of dust and/or smoke passing through the dust passage route may be detected based on the received-light output level at light-receiving element 105a. 
However, with the foregoing conventional optoelectronic dust sensor, because the dust passage route is provided within main body housing 101, dust and/or smoke being made to pass through the dust passage route, there is a tendency for dust and/or smoke to accumulate within main body housing 101 and for deposits to collect therein. In the event that the amount of deposits collected within this main body housing 101 becomes too large, it will sometimes be the case that a portion of the light from light-emitting unit 104 is reflected in diffuse fashion by the deposits which have collected within main body housing 101 and is incident on light-receiving unit 105, this then causing an increase in the amount of light received at light-receiving unit 105 and contributing to mistaken detection of dust and/or smoke.
And yet, at the foregoing conventional optoelectronic sensor, there having been no consideration made with respect to removal of deposits that have collected within main body housing 101, removal of deposits has been difficult; a vacuum cleaner or the like being employed in practice to suck away deposits by way of the small respective dust passage holes 102a, 103a. 
The present invention was therefore conceived in light of the foregoing conventional problems, it being an object thereof to provide an optoelectronic dust sensor permitting easy removal of deposits that have collected within the main body housing thereof, and air conditioning equipment in which such optoelectronic dust sensor(s) is/are installed.